This invention relates to the winding of large-diameter cable on drums, and more particularly to apparatus for automatically controlling a traversing operation, of the type capable of controlling the formation, by cable coming from a production or treatment line, of a winding of successive turns and layers on the core of a drum to which the cable is attached, the drum being rotatingly driven about its axis on a support, and the cable passing through a cable-guide which is movable relative to the drum support in a direction parallel to the axis of the drum and guides the cable at a predetermined approach angle.
The term "large-diameter cable" is intended to mean insulated electric cable having an outside diameter of more than 10 mm. In general, however, the diameter of the cable does not exceed 60 mm. Normally, such cable is produced in the longest possible lengths and is wound on drums which are often as large as several meters in diameter. The winding machines holding these drums and rotating them are massive pieces of equipment which require large and powerful motors to drive them.
For example, the present assignee's U.S. Pat. No. 3,948,462 describes a winding machine of this kind in which the traversing carriage is supported by a rail parallel to the axis of the drum support, and the drum support itself comprises two mutually independent uprights capable of moving on rails which are likewise parallel to that axis. It is thus possible to carry out either traverse operations in which the traversing carriage and, consequently, the cable-guide move parallel to the axis of the drum along its entire length, or operations known as self-traversing, in which the traversing carriage remains stationary and it is the drum-support assembly which effects a translatory movement in front of the traversing carriage.
It has long been known how automatic traverse operations can be carried out on small winding machines intended to produce reels of telephone wire, for example, where the flanges of the reels are up to 40 cm. in diameter. In this case, the traversing carriage moves in front of the reel support, and its drive is connected to the reel drive, so that the traversing speed is proportional to the winding speed.
When it comes to winding large-size cable, however, it is not possible to control an automatic traverse operation simply by making the speed of the traversing carriage proportional to the speed of rotation of the drum; and until now it has been necessary for the traverse operation to be under the constant supervision of an operator.
To illustrate the mechanical conditions under which the successive turns of cable are laid on the drum core, we shall first consider FIG. 1 of the accompanying drawings, which shows schematically a drum 1 on which a cable 2 is being laid turn by turn. Drum 1 comprises a cylindrical core 3 and two disk-shaped end flanges 4 and 5. The leading end of a cable 2 is hooked into a hole 6 in drum core 3. Drum 1 is rotated in the direction indicated by arrow A so that a first turn touching flange 4 is laid down. At the end of this first turn, however, cable 2 must be deviated toward the left, as viewed in FIG. 1, so that the second turn will be positioned parallel to and touching the first turn. Thus, the winding of the cable on the drum core is not made up of successive, parallel helices but instead forms a series of irregular curves. In conventional winding machines where the operation is constantly monitored by an operator, the incoming portion of cable, designated as 7, is kept at a suitable angle called the approach angle, designated as r in FIG. 1. It will be obvious that when a full layer of turns has been laid down, the angle of portion 7 relative to a plane perpendicular to the axis of the drum has to be changed, and when the last turn of a layer is being laid down, that angle must be reduced to zero. Then, when the first turn of the following layer has been formed, portion 7 of the cable must be guided in such a way that the approach angle is reversed, for while a layer is being formed from left to right, that angle must be inverted as compared with its value during the formation of a layer from right to left.
It is an object of this invention to provide improved apparatus for the automatic control of a traverse operation, suitable for equipping large winding machines which are able to support and rotate drums intended to receive considerable lengths of cable having a diameter of more than 10 mm.
To this end, in the control apparatus according to the present invention, of the type initially mentioned, the improvement comprises projection means for forming on a receiving surface an image of the silhouette of a predetermined zone of the winding, sensing means sensitive to the image and capable of generating an electrical signal representing the silhouette, means for analyzing and processing the signal and supplying control signals, and drive means responsive to the control signals for causing relative movements between the cable-guide and the drum support as a function of the result of the analysis.